A couple of weeks ago i did some pressure tests on the old and the new fuel pumps. The idea was to check the pressure of the old NOS one and set the new Holley Blue to give the same pressure.
However, the tests showed that both pumps were poor at priming themselves (expelling the air and actually pumping fuel). The problem is made worse on my system in that the fuel system is the dead head type where there is no return for fuel back to the tank, so the air in the pump and lines has nowhere to go. This is the way i have always run it and the way NOS expected their pump to be used.
Once primed the small NOS pump works flawlessly, and without a regulator it produces a consistent 4.5psi. The Holley however seemed very finicky, it took just about forever to prime properly, even when not dead headed. Furthermore you can switch it on one time and get say 9psi. switch it off and immediately back on and it can make 1 or 2 psi different.
As a result i decided i liked the NOS pump better, it delivers more than enough fuel for my small nitrous system, is tiny and super lightweight compared to the Holley, and so i purchased a brand new one from Earls.
It will be relocated on the bike and be positioned in a way that will hopefully allow air to escape back up to the tank. Plus i'm adding a tee right in front of the solenoid so i can check the pressure to the solenoid before a run.
The RG125 forks are now rebuilt and back on the bike. It took some research to find forks from a bigger bike that would have springs the same diameter, there aren't many that use 39mm stanchions, but a pair of stuffed FZ750 forks were bought off eBay for £13 and finally i have springs of the perfect diameter.
I had to cut them down by quite a bit and adjusted the preload with sections of tube and guesswork. The result is a much stiffer set of forks and when the bike is at rest there is pretty much no compression of the forks, i reckon they will about right. Not like i'm a suspension expert but i've ridden a bike or 2 and you get a feel for these things!
As well as fitting the new pump i also have a new set of solenoids, and new Micro relays to fit, plus - thanks to
Roger Upperton i also have a new double ignition shift kill switch to try, so a little bit of wiring modification is on the agenda for this coming weekend.
The kill switch features 2 microswitches that are activated one after the other. The theory is that the Nitrous will get a slightly longer kill than the ignition and is my second attempt at stopping the backfires that are a pain in the butt!
My prediction of more entries in Competition bike was poor. There are still only 6 entries on the final list. Why this year should be different to the last I'm not sure, but an 8 bike field would add a lot more to the competition.
Just one week to go to the next race meeting which is the Open sport Nationals held at Shakespeare County Raceway, Stratford Upon Avon.
Version 2 of the entry list is out and shows only 6 bikes in Competition bike. Entries are still open however so there may be one or two more.
I've re-employed the VFR fuel pump. It does carb supplying duties, and also double as fuel cutoff. The bracket was a bit unnecessary, a pair of cable ties would have done!
The Nitrous pressure gauge used to be mounted on the bottle. But it's now on a short hose and mounted on the left where it can be seen easily.
And finally, here's the double kill switch i'll be trialling in an attempt to stop the nitrous pops!
